9/11=terrorism?

The bombing of Hiroshima and Nagasaki killed at least 100000 civilians. These were not military targets. Japan was a military dictarorship at the time, the people had not elected the people in power and had no authority to sway them in any way, and therefore not responsible for any action that regime took.
They were not warned that their homes would be bombed by a weapon that their shelters could not protect them from.
How would you defend this without justifying the attack on WTC on 9/11?

Yes, the US did a lot of bad shit during the war (see: Dresden, Hiroshima).  But during the war, we were literally fighting to save entire countries.  It's all about scale.  I am a moral relativist because morals are, in fact, relative.  Bin Laden was fighting to save his way of life, sure, but I'm sorry, the needs of a few hundred radicals don't match up to the needs of the countries involved in WW2.